Regal Moth

The regal moth, also known as the royal walnut moth, is truly stunning in both size and beauty.  This nocturnal giant becomes active at dusk and flies all night.  Found throughout Ohio, the moth’s distribution is closely tied to its larval host trees.  They are found in deciduous forests in the eastern U.S. from New Jersey to Missouri and south to eastern Texas and central Florida.  These forests contain their preferred host tree species – walnut and hickory.  But other trees such sweetgum, sumac, and persimmon, are also commonly used.  Although they prefer moist bottomland forests and mature upland woodlands they might be seen in suburban areas with mature trees.

This nocturnal beauty is enormous with a wingspan of 4 to 6 inches.  Females are larger than males.  Their forewings are usually a deep olive-brown or black with prominent orange veins and yellow spots.  The hindwings are more uniformly orange with yellow and dark spots.  Their body is stout and covered in orange and yellow hairs giving it a fuzzy appearance.  These very vivid and contrasting colors are a warning to predators that the moth may be toxic or poisonous or just distasteful.  Of course, this is just a smokescreen as the moth is none of these things.  Adults have no functioning mouth parts or digestive systems.  They have only the energy they stored during their caterpillar stage.  Their adult lifespan is very short – only a week or two.  They have only one purpose, find a mate and reproduce.  

As impressive as the regal moth is, their caterpillar called the hickory horned devil is equally impressive.  After hatching the caterpillar spends about 37 to 42 days eating and growing, molting several times as it increases in size.  Early-stage caterpillars look like bird droppings – an effective camouflage as they munch on leaves.   By the time these caterpillars mature they are huge.  Mature caterpillars are enormous, 5-to 6 inches long and about ¾ inch in diameter.  They’ve been compared in size to a hotdog and described as a scary dragon.  Their body color ranges from deep blue-green to tan with up to 5 pairs of long, curving, orange, hornlike structures over the back of its thorax with the rest of the body covered with shorter black spikes.  It looks ferocious, but it’s not.  Mature caterpillars leave their host trees to burrow into the soil to pupate in the ground.  This is when most people will see these amazing creatures as they are looking for a place to dig into the soil.  They overwinter as pupae.

Regal moths and their caterpillars are an important part of the food chain. They’re threatened by habitat loss, climate change, pesticides, herbicides, and light pollution.  They mate and lay their eggs in the dark of night.  Their caterpillars feed at night.  All moths are drawn to bright lights at night, and the regal moth is no different.  Moths drawn to light are not mating.  Under the light they will die due to increased predation or exhaustion before daylight.  Unfortunately, under a bright light is the only place many people see a regal moth.  Let’s help these amazing moths thrive by protecting dark skies so that they can continue to play their role in the ecosystem.